Study on Bending of Woven Fabrics Using Linear Viscoelasticity Theory

The bending behavior of woven fabrics under low curva-ture conditions has been analyzed by linear viscoelastictheory.The fabric is assumed to behave viscoelasticallyand to be subjected to frictional restraints in bending de-formation.The frictional restraint is considered to beproportional to the curvature and can be described by africtional moment.A model has been constructed by astandard three-element solid model and a paralleledfrictional sliding element.The equations of the model fora cyclic curvature variation are derived.A set of param-eters of the equations for each fabric has been obtainedexperimentally.Predictions of the bending rigidity andhysteresis for wool,cashmere,wool/polyester blended,polyester and cotton fabrics are made,displaying verygood agreement with the experimental observations.     

Amyloid beta-peptide is produced by cultured cells during normal metabolism.

Alzheimer's disease is characterized by the extracellular deposition in the brain and its blood vessels of insoluble aggregates of the amyloid beta-peptide (A beta), a fragment, of about 40 amino acids in length, of the integral membrane protein beta-amyloid precursor protein (beta-APP). The mechanism of extracellular accumulation of A beta in brain is unknown and no simple in vitro or in vivo model systems that produce extracellular A beta have been described. We report here the unexpected identification of the 4K (M(r) 4,000) A beta and a truncated form of A beta (approximately 3K) in media from cultures of primary cells and untransfected and beta-APP-transfected cell lines grown under normal conditions. These peptides were immunoprecipitated readily from culture medium by A beta-specific antibodies and their identities confirmed by sequencing. The concept that pathological processes are responsible for the production of A beta must not be reassessed in light of the observation that A beta is produced in soluble form in vitro and in vivo during normal cellular metabolism. Further, these findings provide the basis for using simple cell culture systems to identify drugs that block the formation or release of A beta, the primary protein constituent of the senile plaques of Alzheimer's disease.     

Observation of scale invariance and universality in two-dimensional Bose gases

The collective behaviour of a many-body system near a continuous phase transition is insensitive to the details of its microscopic physics; for example, thermodynamic observables follow generalized scaling laws near the phase transition. The Berezinskii-Kosterlitz-Thouless (BKT) phase transition in two-dimensional Bose gases presents a particularly interesting case because the marginal dimensionality and intrinsic scaling symmetry result in a broad fluctuation regime and an extended range of universal scaling behaviour. Studies of the BKT transition in cold atoms have stimulated great interest in recent years, but a clear demonstration of critical behaviour near the phase transition has remained elusive. Here we report in situ density and density-fluctuation measurements of two-dimensional Bose gases of caesium at different temperatures and interaction strengths, observing scale-invariant, universal behaviours. The extracted thermodynamic functions confirm the existence of a wide universal region near the BKT phase transition, and provide a sensitive test of the universality predicted by classical-field theory and quantum Monte Carlo calculations. Our experimental results provide evidence for growing density-density correlations in the fluctuation region, and call for further explorations of universal phenomena in classical and quantum critical physics.     

多项式微分系统的不变直线的不同斜率的最大个数

本文证明了公式β（ｎ）＝σ（ｎ－１）＋１其中α（ｎ－１）是ｎ－１次多项式微分系统的不为直线的最多条数，βｎ）是ｎ次多项式微分系统的不变直线的不同斜率的最大个数。这里假设所讨论的多项式系统只有限条不变直线。     

中国山茶科新植物(英文)

本文记载了山茶科山茶属油茶组2新种及1新变种,毛蕊茶组1新种;木荷属1新种,它们分别产于江西、广西及广东。     

Targeting of cell-surface beta-amyloid precursor protein to lysosomes: alternative processing into amyloid-bearing fragments.

Progressive cerebral deposition of the amyloid beta-peptide is an early and invariant feature of Alzheimer's disease. The beta-peptide is released by proteolytic cleavages from the beta-amyloid precursor protein (beta APP), a membrane-spanning glycoprotein expressed in most mammalian cells. Normal secretion of beta APP involves a cleavage in the beta-peptide region, releasing the soluble extramembranous portion and retaining a 10K C-terminal fragment in the membrane. Because this secretory pathway precludes beta-amyloid formation, we searched for an alternative proteolytic processing pathway that can generate beta-peptide-bearing fragments from full-length beta APP. Incubation of living human endothelial cells with a beta APP antibody revealed reinternalization of mature beta APP from the cell surface and its targeting to endosomes/lysosomes. After cell-surface biotinylation, full-length biotinylated beta APP was recovered inside the cells. Purification of lysosomes directly demonstrated the presence of mature beta APP and an extensive array of beta-peptide-containing proteolytic products. Our results define a second processing pathway for beta APP and suggest that it may be responsible for generating amyloid-bearing fragments in Alzheimer's disease.     

金花茶组植物订正

本文订正了山茶属金花茶组的系统分类,合并了7个异名种和5个变种,另把2个变种提为新组合种。文章对金花茶组的特性和变异性作了较全面的探讨,然后提出合并和提升的依据。     

萃取干燥处理对UHMW-PE冻胶丝拉伸性能的影响

为了改善 UHMW—PE 冻胶丝的拉伸性能,本文对 UHMW—PE 冻胶丝的萃取和干燥工艺条件进行了研究.结果表明冻胶丝的最大拉伸倍数依赖于萃取和干燥条件,如:萃取剂、干燥过程中的限制收缩率、干燥温度和干燥时间.在萃取和干燥过程中的过量收缩会引起冻胶丝内部缺陷的产生,导致冻胶丝可拉伸性的恶化.本文以最优化实验,获得了以溶剂汽油为萃取剂对冻胶丝处理的最佳萃取和干燥条件是:多次萃取和5%限制收缩干燥.经最佳实验条件处理的冻胶丝在超高倍拉伸过程中是稳定的,并可制得强度为37.3cN/dtex 和模量为1731.0cN/dtex 的长丝.     

(+)-和(-)-1,1’-联-2-萘酚的立体选择合成

使用光学活性的2-氨基丁醇-1、麻黄素、ψ-麻黄素、酒石酸和谷氨酸在KF·2H_2O存在下分别与Merrifield树脂反应制得8种相应的手征性树脂.由这些树脂和Cu(NO_3)_2作用后生成的Cu(Ⅱ)络合物树脂作为氧化偶合试剂,对2-萘酚的氧化偶合反应具有立体选择效果,可得致电46～58ee%的(+)-或(-)-1,1′-联-2-萘酚。